Atherectomy: The Little Devices that Could

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CVB040108As the incidence of peripheral arterial disease (PAD) rises, endovascular interventions continue to gain wider acceptance. Yet, questions remain regarding which patients benefit most from atherectomy devices.

Complex disease state

PAD is the most common type of peripheral vascular disease, affecting about eight million Americans. By age 65, about 12 to 20 percent of the U.S. population has the disease, which causes a four- to five-times higher risk of heart attack or stroke, according to the American Heart Association.

Traditional treatment such as surgical bypass is effective but invasive. As a result, the endovascular approach to treating PAD has gained increasing acceptance. Between 1996 and 2006, bypass surgery rates decreased 43 percent, while endovascular interventions increased 230 percent per 100,000 patients, and the rate of lower extremity amputation fell by 28 percent (J Vas Surg 2009:50;(1)54-60).

Goodney et al also found that increased numbers in endovascular interventions per 100,000 patients was due to growth in peripheral angioplasty and percutaneous atherectomy. The researchers noted that while percutaneous atherectomy is a new and expensive procedure, its use has increased by more than 4,100 percent.

Based on the clinical literature, atherectomy is successful about 95 percent of the time, but plaque forms again in 20 to 30 percent of the patients, according to Rajesh M. Dave, MD, chair of endovascular medicine at Pinnacle Health Heart and Vascular Institute in Harrisburg, Pa.

Plaque formation in PAD is much more complex than in the coronaries, Dave says. In the lower extremities, plaque is more diffuse. “The femoral-popliteal arteries have a tremendous amount of plaque burden—substantially more so than with coronary artery disease, where the arteries are smaller and the amount is generally limited to the area of blockage. Coronary disease is not nearly as expansive as it is in the peripheral arteries,” Dave explains.

Current PAD treatments do not effectively prevent restenosis, which still remains the single most important predictor of how a patient does after an endovascular interventional procedure, he says. “However, similar to coronary artery disease, the outcome of peripheral interventions has the potential to significantly improve if lumen diameter is expanded and plaque burden reduced. This is where atherectomy is particularly useful.”

Market trends

Peripheral Vascular Key Segments:
2008 In 2008, stents represented 41 percent of peripheral vascular treatment. Overall, endovascular interventions in the last five years have increased more than threefold, while bypass surgery has decreased by 4 percent. Source: Frost & Sullivan
Atherectomy
Peripheral Stents
PTA Balloon Catheter
Stent-Graft SFA
Surgical Grafts
Thrombectomy
The peripheral vascular market is growing, partly due to a huge underserved patient population, according to Venkat Rajan, industry manager for medical devices at Frost & Sullivan.

Specifically, Frost & Sullivan predicts the annual growth rate for atherectomy devices will be around 10 to 12 percent. The firm reported that peripheral stents gained 41 percent of the market share in 2008, with atherectomy devices gaining 13 percent—indicating room for growth, according to Rajan.

Overall, the 2009 market projection was valued at approximately $230 million, with ev3’s FoxHollow leading the way, followed by Spectranetics’ laser device and Boston Scientific’s rotational device. Rajan adds that newer, smaller companies have entered the atherectomy device field over the past year, including Pathway Medical and Cardiovascular Systems, broadening the field of choices.

In August 2009, for example, Pathway introduced a smaller 7 French atherectomy catheter for its Jetstream device, expanding the scope if its use. The Jetstream last year also received FDA clearance for thrombus removal.

Rajan notes that more clinicians are willing to undertake these interventional procedures, abandoning a “wait and watch” approach. In addition, the preference of the various specialists who perform vascular interventions will influence how and when the devices are used. The success of interventional treatment for peripheral vascular disease has specialists jostling for turf.

Vascular surgeons, who traditionally treated peripheral vascular disease, could potentially lose cases to interventional cardiologists. From 2005 to 2008, interventional cardiologists’ volume grew from 38 to 50 percent, whereas vascular surgeons’ volume increased only 10 percent—25 to 35 percent, Frost & Sullivan reports. Interventional radiologists took the biggest hit in this time frame—dropping from 40 to 15 percent.

The trend for interventional cardiologists to enter the peripheral arena will only continue as this market continues to mature, Rajan says, adding that stenting and using atherectomy devices in the peripheries are reimbursable.  

When & where

There are subtle differences among the various devices that steer operators toward one over another. There also are various lesion morphologies that might be better served with one device over another, according to Dave.

For heavily calcified lesions, he suggests the Diamondback 360º orbital system (Cardiovascular Systems), which “spins through the artery, reducing the plaque and calcium. As the calcium is reduced, the arteries can more easily expand with a balloon or a stent, which is almost impossible without it.” Prior to atherectomy devices, interventionalists would inflate balloons in the calcified arteries, “which would end up dissecting, leading to suboptimal stent implantation.”

For thrombotic lesions with underlying plaque and superimposed thrombus, he suggests a laser atherectomy device. Finally, for lesions with “fibrous or soft plaque, which is preferentially on one surface of the vessel, directional atherectomy is very useful,” Dave says.

Rajan notes, “Atherectomy devices are still viewed as specialty devices—used mainly for longer occlusions or chronic total occlusions.” He adds that more clinical trial data need to emerge in this area. With such studies, manufacturers may be able to prove the expanded worth of these devices, beyond their current usages.

Nevertheless, the momentum to use atherectomy devices is growing. The concern regarding long-term patency of stenting and the increased need for reintervention is leading many interventional cardiologists to consider excision of obstructive plaque.

“Overall, atherectomy devices have an important emerging role for complex lesions, especially those extending into tibial vessels,” say Gautam V. Shrikhande, MD, and James F. McKinsey, MD, from the department of vascular surgery at Columbia University in New York City (Semin Vasc Surg 2008;21[4]:204-9).

“Atherectomy devices have the distinct advantage of removing the obstructing atherosclerotic or intimal hyperplastic lesions without the disadvantage of a foreign body such as a stent in the artery,” they wrote. “If reintervention is required after atherectomy, this can generally be accomplished at the same site with low risk of complications or discomfort to the patient. Finally, atherectomy also does not preclude use of bypass for the treatment of peripheral arterial disease nor, in most cases, change the anastomotic sites if surgical bypass is required, in contrast to stenting.”